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J M Steinacker

Publications and source records attributed to J M Steinacker.

At least 19 recordsLinked to original sources
PubMed2005

Thyroid hormones, cytokines, physical training and metabolic control.

During the acute training response, peripheral cellular mechanisms are mainly metabolostatic to achieve energy supply. During prolonged training, glycogen deficiency occurs; this is associated with increased expression of local cytokines, and decreased insulin secretion and beta-adrenergic stimulation and lipolysis in adipose tissue which looses energy. This is indicated by decrease of adipocyte hormone leptin, which has inhibitory effects on excitatory hypothalamic neurons. Leptin, insulin, and cytokines such as interleukin 6 (IL-6) contribute to the metabolic error signal to the hypothalamus which result in decrease of hypothalamic release hormones and sympathoadrenergic stimulation. Thyroid stimulating hormone (TSH) is correlated to the metabolic hormones leptin and insulin, and may be used as indicator of metabolic control. Because the hypothalamus integrates various error signals (metabolic, hormonal, sensory afferents, and central stimuli), the pituitary's releasing hormones represent the functional status of an athlete. Long-term overtraining will lead to downregulation of hypothalamic hormonal and sympathoadrenergic responses, catabolism, and fatigue. These changes contribute to myopathy with predominant expression of slow muscle fiber type and inadequacy in performance. Thyroid hormones are closely involved in the training response and metabolic control.

Animals↗
PubMed2003

Effects of high intensity resistance and low intensity endurance training on myosin heavy chain isoform expression in highly trained rowers.

An important mechanism of muscle adaptation to exercise is the alteration of myosin heavy chain (MHC) isoform expression. This study investigated the effect of a high intensity resistance training (HIRT) and a low intensity endurance rowing (LIER) on MHC isoform expression in highly trained human muscle. Six well-trained male rowers underwent a training program consisting of a 3-week HIRT and a 3-week LIER, each followed by one-week of recovery. Muscle samples were taken from vastus lateralis before and at the end of each training and recovery phase. MHC isoform was analyzed by SDS-PAGE using silver stain and MHC isoform mRNA by RT-PCR. The maximum oxygen uptake and power output did not change after the training. MHC isoform composition did not change over HIRT or LIER, and there was a decrease in MHC I with concomitant increase in MHC IIa after recovery following HIRT. HIRT led to mRNA upregulation of MHC Ialpha, Ibeta and IIx (127 %, 148 % and 117 %, respectively, p < 0.05), but not MHC I protein (60 % vs 62 %, NS), and LIER led merely to MHC Ibeta mRNA upregulation (131 %, p < 0.05). Thus, different responses of MHC isoform expression to HIRT and LIER occurred in the highly trained muscle, and a "ceiling effect" in terms of MHC I expression could be observed. The upregulation of MHC Ialpha mRNA in human skeletal muscle documented in this study may encourage further observations in this field.

Adult↗
PubMed2003

Different effects on human skeletal myosin heavy chain isoform expression: strength vs. combination training.

Myosin heavy chain (MHC) isoform expression changes with physical training. This may be one of the mechanisms for muscular adaptation to exercise. We aimed to investigate the effects of different strength-training protocols on MHC isoform expression, bearing in mind that alpha- MHC(slow) (newly identified MHC isoform) mRNA may be upregulated in response to training. Twelve volunteers performed a 6-wk strength training with maximum contractions (Max group), and another 12 of similar age performed combination training of maximum contractions and ballistic and stretch-shortening movements (Combi group). Muscle samples were taken from triceps brachii before and after training. MHC isoform composition was determined by SDS-PAGE silver staining, and mRNA levels of MHC isoforms were determined by RT-PCR. In Max group, there was an increase in MHC(2A) (49.4 to 66.7%, P < 0.01) and a decrease in MHC(2X) (33.4 to 19.5%, P < 0.01) after training, although there was no significant change in MHC(slow). In Combi group, there was also an increase in MHC(2A) (47.7 to 62.7%, P < 0.05) and a decrease in MHC(slow) (18.2 to 9.2%, P < 0.05) but no significant change in MHC(2X). An upregulation of alpha-MHC(slow) mRNA was, therefore, found in both groups as a result of training. The strength training with maximum contractions led to a shift in MHC isoform composition from 2X to 2A, whereas the combined strength training produced an MHC isoform composition shift from slow to 2A.

Adult↗
PubMed2002

HSP70 expression in skeletal muscle of patients with peripheral arterial occlusive disease.

OBJECTIVES: heat shock protein (HSP70) has been studied in the ischaemic myocardium and proven to provide protection against ischaemia. However, HSP70 in ischaemic skeletal muscle in patients with peripheral arterial occlusive disease (PAOD) has not been reported. METHODS: thirty-four patients with PAOD (Fontaine's criteria: stage II: 15; III: 9 and IV: 10, respectively) and ten non-PAOD controls were enrolled in the study. Calf muscle samples were taken. HSP70 was quantitated by SDS-PAGE using ultrasensitive silver staining with reference to a series of standard HSP70, and HSP70 mRNA was estimated using RT-PCR. RESULTS: in comparison with the controls [median with range: 24.8 (14.1-35.6) ng in 2.5 microg total protein], HSP70 was increased significantly in PAOD [stage II: 93.1 (62.7-114.3); stage III: 110.1 (89.7-134.5) and stage IV: 77.4 (67.3-101.1)]. Similar results were obtained with HSP70 mRNA. CONCLUSIONS: HSP70 is increased in the ischaemic skeletal muscle in patients with PAOD, and HSP70 expression is different with regard to clinical stages, and the upregulation of HSP70 mRNA implies that the expression of HSP70 seems to be regulated at transcriptional level.

Aged↗
PubMed2002

Training intensity influences leptin and thyroid hormones in highly trained rowers.

Leptin (L) is associated with body-weight-regulating and adipostatic functions. Its receptors also may be found centrally. Thyroid hormones regulate metabolic processes mainly by binding at peripheral receptors. Aim of this study was to show if there is a link between those central and peripheral regulation systems and to investigate the influence of different training intensities on L and the hypothalamic-thyroid-axis (HTA) in highly trained rowers. Six rowers (18.9 +/- 2.6 y; BMI 22.8 +/- 2.1 kg/m (2)) undertook high intensity resistance training (RT) for three weeks followed by three weeks of endurance training (ET). After each training cycle the subjects had one week for recovery (R1, R2). Blood samples were taken before and at the end of RT, R1, ET and R2. L, thyroid stimulating hormone (TSH), free T3 (fT3) and free T4 (fT4) were measured. After RT, a significant reduction in L, TSH and fT3 was found (p < 0.05). fT4 was unchanged. L remained decreased until the end of R1. After ET, a significant increase of TSH was found. L correlated to basal TSH levels (r = 0.49, p = 0.006) during R. BMI and body fat were unchanged throughout the study and were not correlated with hormonal levels. We speculate a high energy flux during intensified training (RT) caused the decrease of L and the HTA, independent of BMI or body fat. Thus, we conclude a depression of L and HTA is associated with training intensity.

Adolescent↗
PubMed2002

Erythropoiesis and performance after two weeks of living high and training low in well trained triathletes.

The purpose of our study was to evaluate hematologic acclimatization during 2 weeks of intensive normoxic training with regeneration at moderate altitude (living high-training low, LHTL) and its effects on sea-level performance in well trained athletes compared to another group of equally trained athletes under control conditions (living low - training low, CONTROL). Twenty-one triathletes were ascribed either to LHTL (n = 11; age: 23.0 +/- 4.3 yrs; VO 2 max: 62.5 +/- 9.7 [ml x min -1 x kg -1]) living at 1956 m of altitude or to CONTROL (n = 10; age: 18.7 +/- 5.6 yrs; VO 2 max: 60.5 +/- 6.7 ml x min -1 x kg -1) living at 800 m. Both groups performed an equal training schedule at 800 m. VO 2 max, endurance performance, erythropoietin in serum, hemoglobin mass (Hb tot, CO-rebreathing method) and hematological quantities were measured. A tendency to improved performance in LHTL after the camp was not significant (p < 0.07). Erythropoietin concentration increased temporarily in LHTL (Delta 14.3 +/- 8.7 mU x ml -1; p < 0.012). Hb tot remained unchanged in LHTL whereas was slightly decreased from 12.5 +/- 1.3 to 11.9 +/- 1.3g x kg -1 in CONTROL (p < 0.01). As the reticulocyte number tended to higher values in LHTL than in CONTROL, it seems that a moderate stimulation of erythropoiesis during regeneration at altitude served as a compensation for an exercise-induced destruction of red cells.

Acclimatization↗
PubMed2001

Changes in skeletal muscle heat shock proteins: pathological significance.

In response to stress, cells rapidly produce a series of new proteins known as heat shock proteins (HSP). HSPs are considered to be molecular chaperones which play a universal role in maintaining cellular homeostasis. It is known that different HSPs are expressed in skeletal muscle, namely, small HSPs (including ubiquitin, alpha B- crystallin, HSP20 and HSP 27), HSP70, HSP60 and HSP90. Skeletal muscle is a complex and heterogeneous system in that its contractile proteins are made of different isoforms to form various muscle fibre types, and each type of muscle fibre has its own histochemical and functional characteristics. It seems that the induction of HSPs differs with muscle fibre type suggesting HSP expression is muscle fibre type specific. HSPs have been shown to respond in muscle diseases and following exercise. However, the molecular mechanisms of HSP induction, regulation and its role in maintaining the muscle function, are not completely understood. Relatively few studies of HSP have been conducted in human skeletal muscles. This review discusses the significance of changes of HSPs in skeletal muscle in both physiological and pathological conditions.

Animals↗
PubMed2001

Effect of exercise intensity on the changes in alveolar slopes of carbon dioxide and oxygen expiratory profiles in humans.

The slope of the expired alveolar partial pressure of carbon dioxide profile increases during exercise. Its relationship to metabolic rate, however, remains to be determined at high exercise intensities. We therefore determined the slope of alveolar partial pressures of carbon dioxide and oxygen (PACO2, PAO2, respectively) during incremental cycle ergometer exercise (an increment of 40 W each minute) to exhaustion in 11 normal subjects. The PACO2 and PAO2 increased as linear functions of carbon dioxide production and oxygen uptake (VO2), respectively, up to the estimated lactate threshold (thetaLa-). At higher intensities PACO2 increased disproportionately but PAO2 continued to increase at the same rate in 7 subjects but increased more rapidly in the remainder. The rate of change in PACO2 per unit rate of change in VO2 averaged 3.15 (SD 1.05) (mmHg.s(-1)). (l.min(-1))-1 while the rate of change in PAO2 per unit rate of change in VO2 averaged -3.53 (SD 0.79) (mmHg.s(-1)) (l.min(-1))-1 over this range. The more rapid increase in PACO2 above thetaLa- was consistent with an accelerated CO2 exchange, whereas the more rapid rate of change in PAO2 in 3 of the subjects may have reflected the development of an increased distribution of the ventilation perfusion ratio in addition to the effects of hyperventilation.

Adolescent↗
PubMed2000

Human skeletal muscle HSP70 response to physical training depends on exercise intensity.

We have previously reported that HSP70 in human skeletal muscle could be induced by training. However, whether HSP70 induction is dependent upon exercise volume or exercise intensity remains unknown. The aim of the present study was to investigate the relationship between HSP70 and training intensity in rowers. Fourteen well-trained male rowers were divided into two groups (group A, n = 6; group B, n = 8). Group A performed higher intensity exercise during 1st phase, whereas group B performed higher intensity exercise during 2nd training phase. Training volume in 2nd phase increased in both groups. Both training intensity and volume were reduced in 3rd phase. Muscle samples were taken from m. vastus lateralis by fine needle biopsy before training, at the end of the 1st, 2nd and 3rd training phases. HSP70 was quantitatively determined using SDS-PAGE with silver stain. In group A, HSP70 increased significantly from 38 +/- 12 etag before training to 59 +/- 16 etag at the end of the lst training phase (loaded total protein 2.5microg), and decreased afterwards. In group B, HSP70 increase (from 36 +/- 11 etag to 50 +/- 13 etag) in the 1st phase was significantly smaller, there was a further increase of HSP70 in the 2nd phase (60 +/- 14 etag). At the end of the training, HSP70 decreased in both groups. Thus, HSP70 response to training seems to be dependent upon exercise intensity.

Adolescent↗
PubMed2000

Lactate concentration in plasma and red blood cells during incremental exercise.

The purpose of this study was to investigate the distribution of lactate in plasma and red blood cells (RBC) in capillary blood during and after incremental exercise. We measured capillary plasma lactate and whole blood lactate of 10 subjects during incremental treadmill running and the first 20 min of recovery. To minimize lactate exchange from plasma to RBC between sampling and analysis, a recently developed rapid plasma separation method was used. RBC lactate was calculated. The RBC/plasma lactate concentration ratio decreased from 1.0 (0.85-1.28) before to 0.37 (0.25-0.45) after exhaustive exercise (plasma lactate 15.9 (12.2-19.5)mmol x I(-1), RBC lactate 4.8 (4.0-7.0) mmol x 1(-1)), thus showing that capillary plasma lactate increased much more rapidly than intracellular lactate during incremental exercise. In the first 5 minutes of recovery intracellular lactate still rose while plasma lactate already declined. Then both decreased while the concentration ratio as well as the absolute concentration gradient remained nearly constant (ratio 20 min after exercise termination: 0.43 (0.19-0.54).

Adolescent↗
PubMed2000

Expression of myosin heavy chain isoforms in skeletal muscle of patients with peripheral arterial occlusive disease.

PURPOSE: Peripheral arterial occlusive diseases (PAODs) not only compromise blood flow but lead to a series of subsequent metabolic and structural changes in the relevant muscles. Changes in myofibrillar proteins (eg, of myosin heavy chain [MHC] isoforms), one of the determinants of muscle structure as well as of muscular function, have not been reported in patients with PAOD and were therefore the aim of this study. METHODS: Thirteen consecutive patients with PAOD were examined (clinical stage according to Fontaine II, three patients; III, three patients, and IV, seven patients) and compared with five age-matched control patients who had been in traffic accidents. A calf muscle sample (gastrocnemius muscle) in the ischemic region was taken for MHC isoform analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis and silver stain, and the relative content of MHC isoforms was measured. RESULTS: Compared with the control patients, there was no significant change of MHC isoforms in patients with PAOD II. In patients with PAOD III, MHC IIb decreased significantly (P <.05) although MHC IIa remained unchanged; in patients with PAOD IV, both MHC IIa and IIb decreased significantly (P <.05). Accordingly, there was a progressive increase of the relative amount of MHC I with more critical ischemia in PAOD. CONCLUSION: In patients with PAOD, the content of MHC II decreased with a higher grade of ischemia. That seems to be consistent with an increased resistance to ischemia for myosin isoforms in the order of I more than in IIa more than IIb. Whether the decrease of MHC II in patients with PAOD is related to atrophy of muscle fibers or to muscle-fiber transition must be investigated further.

Aged↗
PubMed2000

Training of junior rowers before world championships. Effects on performance, mood state and selected hormonal and metabolic responses.

BACKGROUND: Few data have been published on training of competitive athletes and about metabolic, hormonal and psychological reactions to overreaching (transient over-training) and tapering in successful athletes. METHODS: Training was recorded and effects on mood state and metabolic and hormonal responses were examined in 10 rowers and spares of the coxed eight during preparation for the World Championships 1995. Mood state was determined using the Recovery-Stress-Questionnaire for Athletes. Resting morning blood parameters as well as performance were measured every week over a period of five weeks. RESULTS: Very high training loads of approximately 3.2 hours per day were sustained for 18 days. Maximum performance (Pmax) and maximum lactate (Lamax) were decreased during high-load training phases (overreaching), Pmax, Lamax and endurance increased after the tapering period. There were decreases in gonadal and hypothalamic steroid hormones (fsh, 1h, prolactin, testosterone) during overreaching and increases in these hormones in tapering. Both performance and hormonal indices of training load were reflected by deterioration of recovery in the Recovery-Stress-Questionnaire for Athletes. CONCLUSIONS: Clear signs of overreaching were found after 18 days of intense training of about 3 h.d(-1) in these highly-trained athletes, i.e. decreases in performance, gonadal and hypothalamic steroid hormones and deterioration of recovery in the psychological questionnaire. After tapering values returned to baseline values before the World Championship. The findings indicate that overreaching is an integral part of successful training regimens and can be analyzed by a multi-factorial approach involving biological and psychometric data.

Adolescent↗
PubMed1999

Carbon dioxide storage and nonbicarbonate buffering in the human body before and after an Himalayan expedition.

Before and 7-12 days after an Himalayan expedition CO2 equilibration curves were determined in the blood plasma of 12 mountaineers by in vitro and in vivo CO2 titration; in vivo osmolality changes (delta Osm x deltaPCO2(-1), deltaOsm x delta pH(-1), where PCO2 is the partial pressure of CO2) during the latter experiments yielded estimates of whole body CO2 storage. In vitro -delta[HCO3-] x delta pH(-1) [nonbicarbonate buffer capacity (beta) of blood] was increased 7 days after descent [before 31.3 (SEM 0.4) mmol x kgH2O(-1), after 38.3 (SEM 3.9) mmol x kgH2O(-1); P<0.05] resulting from an increased proportion of young erythrocytes; in additional experiments an augmented beta was found in young (low density cells) compared to old cells [<1.097 g x ml(-1): 0.216 (SEM 0.028) mmol x gHb(-1), >1.100 g x ml(-1): 0.145 (SEM 0.013) mmol x gHb(-1), where Hb is haemoglobin; P < 0.02]. In spite of increased Hb mass in vivo delta[CO2total] x deltaPCO2(-1) [0.192 (SEM 0.010) mmol x kgH2O(-1) x mmHg(-1)] and -delta[HCO3-] x delta pH(-1) [17.9 (SEM 1.0) mmol x kgH2O(-1)] as indicators of extracellular beta rose only slightly after altitude (7 days +16%, P<0.02; +7%, NS) because of haemodilution. The deltaOsm x deltaPCO2(-1) [0.230 (SEM 0.015) mosmol x kgH2O(-1) x mmHg(-1)] remained unchanged. Prealtitude differences in deltaOsm x delta pH(-1) between hypercapnia [-41 (SEM 5) mosmol x kgH2O(-1)] and hypocapnia [-20 (SEM 3) mosmol x kgH2O(-1); P<0.01] disappeared temporarily after return since the former slope was reduced. The high value during hypercapnia before ascent probably resulted from mechanisms stabilizing intracellular pH during moderate hypercapnia which were attenuated after descent.

Acclimatization↗
PubMed1999

Human skeletal muscle HSP70 response to training in highly trained rowers.

Previous studies have demonstrated exercise-induced heat shock protein 70 (HSP70) in animals. The purpose of this study was to investigate human skeletal muscle HSP70 response to rowing training. Ten male rowers trained for 4 wk with different forms, durations, and intensities of exercise. Biopsy was performed in the right musculus vastus lateralis before training and at the end of each week. HSP70 in 5 microg of total protein from the muscle sample was determined by using Western blot and immunodetection with chemiluminescence technique, by means of laser densitometer referring to a series of known standard HSP70. Compared with pretraining (100%), HSP70 increased during training (181, 405, 456, and 363% from the first to fourth training week, respectively) with the maximum HSP70 production at the end of second training week. Thus HSP70 is induced in highly trained human muscle by long-term training.

Adolescent↗
PubMed1998

Effect of "living high-training low" on the cardiac functions at sea level.

Living high-training low (LHTL), living at high altitude and training at sea level, is reported to be beneficial in enhancing physical performance. Effect of LHTL on cardiac function which is one of major determinants in performance, however, was not examined. To address this issue, 21 well-trained triathletes divided into control (n = 10, living and training at sea level) and LHTL group (living at 1980 m altitude > or = 12 hrs/day and training at sea level) were Doppler echocardiographically examined before and at the end of the two-week program. Heart rate and blood pressure did not change in both groups. At end of the training, left ventricular endsystolic diameter of LHTL group was smaller than that of controls (32 vs 34 mm, P < 0.05). Shortening fraction and ejection fraction in LHTL group increased by 9% and 17 %, respectively, P < 0.05. Preejection period/ejection time was more greatly reduced in LHTL group (P < 0.05). Stroke volume and cardiac output in LHTL increased. Diastolic function was not significantly affected by LHTL. These results suggest that LHTL produced an improvement of systolic function underlined by incremented left ventricular contractility, which might be associated with increased beta-adrenergic receptor or an improved myocardial energy utilization.

Adult↗
PubMed1998

Training of rowers before world championships.

In rowing, static and dynamic work of approximately 70% of the body's muscle mass is involved for 5.5 to 8 min at an average power of 450 to 550 W. In high load training phases before World Championships, training volume reaches 190 min.d-1, of which between 55 and 65% is performed as rowing, and the rest is nonspecific training like gymnastics and stretching and semispecific training like power training. Rowing training is mainly performed as endurance training, rowing 120 to 150 km or 12 h.wk-1. Rowing at higher intensities is performed between 4 and 10% of the total rowed time. The increase in training volume during the last years of about 20% was mainly reached by increasing nonspecific and semispecific training. The critical borderline to long-term overtraining in adapted athletes seems to be 2 to 3 wk of intensified prolonged training of about 3 h.d-1. Sufficient regeneration is required to avoid overtraining syndrome. The training principles of cross training, alternating hard and easy training days, and rest days reduce the risk of an overtraining syndrome in rowers.

Adult↗
PubMed1998

Lung diffusing capacity and exercise in subjects with previous high altitude pulmonary oedema.

Subjects with a history of high-altitude pulmonary oedema (HAPE) have increased pulmonary artery pressure and more ventilation-perfusion (V'A/Q') inhomogeneity with hypoxia and exercise. We used noninvasive methods to determine whether there are differences in the pulmonary diffusing capacity for carbon monoxide (DL,CO) and cardiac output (Q') during exercise, indicative of a more restricted pulmonary vascular bed in subjects with a history of HAPE. Eight subjects with radiographically documented HAPE and five controls with good altitude tolerance had standard pulmonary function testing and were studied during exercise at 30 and 50% of normoxic maximal oxygen consumption (V'O2) at an inspiratory oxygen fraction of 0.14 and 0.21. DL,CO and Q' were measured by CO and acetylene rebreathing techniques. HAPE-resistant subjects had 35% greater functional residual capacity than HAPE-susceptible subjects. Vital capacity and total lung capacity were also 7-10% greater. There were no differences in airflow rates or resting diffusing capacity. However, DL,CO in HAPE-susceptible subjects was lower in hypoxia and with exercise, and showed less increase (32 versus 49%) with the combined stimulus of hypoxic exercise. HAPE-susceptible subjects had smaller increases in stroke volume, Q', and ventilation during exercise. The findings are consistent with lower pulmonary vasoconstriction, greater vascular capacitance and greater ventilatory responsiveness during exercise in subjects who are resistant to high-altitude pulmonary oedema. Their larger lung volumes suggest a constitutional difference in pulmonary parenchyma or vasculature, which may be a determinant of high-altitude pulmonary oedema resistance.

Adult↗